1. Technical Field
The present invention relates to a urinal, and more particularly, to a urinal having a high-frequency sensor.
2. Related Art
When a human body and a liquid flow are detected with high precision using a Doppler frequency signal from a high-frequency sensor to control an opening and closing of a valve at an appropriate timing, a urinal can be used without wasting cleaning water. Also, when an antenna of the high-frequency sensor is configured by patch electrodes, it is possible to facilitate a decrease in size of the high-frequency sensor.
In the related art, there has been known a urinal cleaning device which controls an opening and closing of a valve provided in a water supply pipe (see e.g., Japanese Patent No. 3740696). In the related art, a liquid flow state in a bowl interior space is calculated based on a Doppler frequency corresponding to a difference between a transmitted wave and a received wave, thereby controlling the valve.
In the urinal, in order to detect a human body or a flow of urine with a low emission power while restraining an erroneous detection, it is necessary to control a direction of a radio beam with high precision. However, there is a limitation upon changing a direction of a radio beam just by controlling an arrangement or a phase of the patch electrodes. When an intersection angle between a radiation surface of the patch antenna and a urinal body is adjusted, it is possible to easily change a direction of the radio beam. In this case, a transmissivity of a dielectric medium decreases due to an excitation direction, and thus a problem arises in that the radio beam cannot be transmitted to an object with a high transmissivity.
Also, JP-A-2005-290718 discloses a urinal in which a radio frequency sensor is placed on a rear upper surface of a urinal body and the radio frequency sensor is configured to radiate a radio beam obliquely. However, according to the configuration of the related art, the radio beam radiated from the radio frequency sensor is reflected at the boundary between the urinal body and an air. Accordingly, in order to detect a human body or a flow of urine, it is necessary to provide a reflector, which is used for reflecting the radio beam reflected at the boundary between the urinal and the air again, over the radio frequency sensor. Thus, since the reflector must be newly provided in the urinal, there is a problem in that design of the urinal is limited.